data: begin of lt_fieldnames occurs 0,
fieldname type c length 100,
end of lt_fieldnames.
data: struct type ref to cl_abap_structdescr,
ls_component type abap_compdescr.


clear: lt_fieldnames[].
struct ?= cl_abap_typedescr=>describe_by_data( lt_itab ).
loop at struct->components into ls_component.
clear lt_fieldnames.
read table gt_fcat     into gs_fcat
with key fieldname = ls_component-name.
lt_fieldnames-fieldname = gs_fcat-seltext_m.
append lt_fieldnames.
endloop.

gt_fcat standart  slis_t_fieldcat_alv tipinde bir tablodur ve   REUSE_ALV_FIELDCATALOG_MERGE fonksiyonu ile doldurulabilir.

lt_fieldnames tablosu gui_download fonksiyonun da kullanılabilir.